Representation of Procedural Knowledge for Expert Systems

Many of the knowledge representation schemes developed in the past have concentrated on declarative knowledge. Many have provided assertional mechanisms for deductive retrieval and some give terminological mechanisms for classification and abstraction. However, none present the system developer with similar sophistication, at a high level of representation, in procedural knowledge. Often the developer is left to write attached procedures or demons using the base language and embedded logical functions or procedures. This paper presents an attempt to elevate procedural knowledge to the same representational level as declarative knowledge, by using a uniform declarative notation. The notation, based on conceptual modelling, has a procedural component giving it the flavor of conceptual programming. It enables complete specification, at a conceptual level, of all aspects of expert knowledge. In particular strategies, which in some systems are represented through "control knowledge", are incorporated naturally into assertional and terminological components. An extended example from shallow fault diagnosis is presented to illustrate the technology.